1. Field of the Invention
This invention is in the field of retractors for use with webs.
2. Description of the Prior Art
The prior automatic locking retractor has a spring biased spool rotatably mounted to a bracket with a web extendable or retractable as the spool is wound. An elongated pawl is pivotally mounted to the bracket and is positioned to engage and lock with the ratchet shaped end flanges of the spool. The pawl is held apart from the flanges until the web is extended to the desired position and then slightly retracted. Thus, the retractor is automatically locked preventing further web extension once the web is pulled outwardly to the desired position and slightly released.
Two main types of automatic locking retractors have been provided for automatically locking the web once pulled outwardly to the desired position. Retractor 11 (FIG. 1) includes a bracket or frame 12 with a pair of spaced apart walls 13 between which is rotatably mounted the spool having web 14 wound thereon. A tongue or lock 15 is mounted to the distal end of the web. Gear 19 rotates with the spool and drives an intermediate gear 20 in meshing engagement with an internal tooth gear 16 rotatably mounted to frame 12. An outward projecting cam 17 fixedly mounted to gear 16 is movable against pawl 18 pivotally mounted between the pair of spaced apart walls 13 and positioned to lockingly engage the opposite ratchet shaped walls of the spool. Such a retractor is shown in the U.S. Pat. No. 3,945,586.
A second type of automatic locking retractor is shown in FIG. 2 and includes a frame 20 between which is rotatably mounted spool 21 having web 22 mounted thereon. Spring 23 is mounted to frame 20 and enclosed within cap 24 and rotatably drives spool 21 to the retracted position. Spool 21 is mounted to the opposite walls of bracket 20 by pin 25. Likewise, pawl 26 is mounted to bracket 20 and is positioned to lockingly engage the teeth 27 of spool 21. A cam plate 28 is mounted to pin 25 between spool wall 29 and wall 38 and is urged against wall 29 by means of a spring. Cam plate 28 has constant diameter except at the location of projection 30 and 31 separated apart by notch 32. The diameter of cam plate 28 is less than the diameter of wall 29 except at the location of projections 30 and 31 and notch 32 thereby ensuring that the teeth of wall 29 project outwardly of cam plate 28. The initial withdrawal of the retractor, that is, outward extension of the web, causes cam plate 28 to rotate positioning projection 30 adjacent pawl 26 and preventing the pawl from pivoting inwardly to engage the spool teeth. Once the web is slightly retracted from the fully extended position, cam plate 28 moves in a clockwise direction as viewed in FIG. 2 positioning notch 32 adjacent pawl 26 and allowing the pawl to pivot inwardly lockingly engaging the spool teeth. Further extension of the web is therefore prevented. Retraction of the web causes clockwise rotation of cam plate 28 positioning projection 31 adjacent the pawl thereby spacing the pawl apart from the teeth and allowing the spool to freely retract without the noise associated with the teeth contacting the pawl. If, however, the web is again extended before fully retracted, cam plate 28 will rotate in a counterclockwise direction as viewed in FIG. 2 causing the pawl to fall into notch 32 preventing further extension of the web.
A problem with the previously described prior automatic locking retractors is that web will continually become tighter or cinch if the web is repeatedly retracted and extended in small amounts. Such cinching may occur if the vehicle seat moves with respect to the retractor. For example, trucks are typically driven over rough terrain resulting in extensive vertical movement of the occupant seat. Thus, once the seat belt harness or web is locked in place and the seat moves downwardly toward the vehicle floor, webbing will be slightly withdrawn into the retractor allowing one or more of the teeth of the spool to move past the pawl. Once the seat moves upwardly, force will be applied to the web to pull the web outwardly; however, at this time projection 31 will move apart from the pawl thereby locking the pawl within notch 32 resulting in tightening of the web. Several or even one such unplanned tightening is uncomfortable to the occupant.
In order to circumvent this problem, the commonly owned U.S. Pat. No. 4,911,377 discloses an anti-cinch locking retractor having a floating cradle upon which the pawl is mounted to allow limited web extension and retraction. Other approaches include the retractor disclosed in U.S. Pat. No. 4,611,770. Disclosed herein is a different solution and approach to the cinching problem.